Gaining a pound doesn't mean you're doing anything wrong; it's most likely just temporary water retention. THe increased intensity of your workout program could be responsible: www.sparkpeople.com/community/ask_the_expe
Or, it could just be your typical monthly hormonal fluctuation. Count back 28 days... did you have your period this time last month?
You can't expect to keep up 5 lb a week losses though, especially not if the weight you have listed to lose in your ticker is correct. As you lose, you will lose more slowly. Fast losses are typical in the beginning as we shed excess water and such, but it balances out to more steady fat loss as we progress. :) What you're seeing was likely rapid water loss, then a little water retention based on exercise. Two weeks isn't enough time to see substantial (1 lb) weight gain from muscle tissue.
I think it's safe to expect around 1-2 lbs per week (closer to 1 as you lose weight) at first, and that will go down as you get closer to your goal weight. Within 10 lbs, you'll be losing 1/4 to 1/2 a lb at most.
Hang in there. It'll be okay. :) Give lifestyle changes 6-8 weeks to show up on the scale. It took time to gain the weight, it'll take time to take it off!